166 Asia is the home of domesticated animals. Australia is the home of the marsupials. The luxuriant vegetation of the south of Africa sustains some of the largest of the mammalia, such as the elephant, rhinoceros, hippopotamus, and giraffe. The entire human family has descended from a single pair or species. The primary races of men are the Caucasian, the Mongo- lian, and the Negro. The secondary races are the Malay, the American, and the Australian. The character of the earth’s mineral products has largely influenced the civilization of man. With a few exceptions, the earth’s mineral products that are of the greatest value to man, such as the precious metals, the valuable metals, building materials, and mineral substances used generally in the arts and in the sciences, are so generally distributed over the earth that practically they are found in all the continents. For a substance to be suitable for building purposes it must possess marked strength, ability to resist a crushing weight placed upon it, and to resist disintegration on long exposure to moisture and change. of temperature. The coast line of the United States is comparatively simple and unbroken. 2 PHYSICAL GEOGRAPHY. The predominant mountains are in the west ; the second- ary mountains are in the east. The great low plains of the United States are the Atlantic coast plain and the plain of the Mississippi Valley.. The Unitéd States lies in the physical north temperate and the physical torrid zone. The climate of the northern half of the Atlantic coast is much colder than that of the northern half of the Pacific. The United States lies in the zone of the variable winds. The heaviest rainfall is on the Pacific coast and near the borders of the Gulf States. There are four distinct: plant regions: prairie, the steppe, and the Pacific. The Territory of Alaska occupies an area of 550,000 square miles. The Territory of Alaska is mainly mountainous. The shore lands of the Arctic are frozen moor-lands like the tundras of Asia., The Yukon and Kuskovim are the principal rivers. Myriads of salmon visit the rivers during the breeding season. Valuable food-fish are found in the waters off the coasts. Numerous fur-bearing animals are found in Alaska. the forest, the GENERAL REVIEW QUESTIONS. —059g400-——. Mathematical Geography. What is the earth’s position in the solar system? How much larger is the sun than the earth? /,? Of what use are latitude and longitude? Distinguish between a map of the earth on a Mercator’ 8 projection, and maps on equatorial and polar and conical projections. Explain the cause of the change of day and night. Explain the causes of the change of seasons. The Land. Enumerate the proofs of the present heated condition of the interior of the earth. What is the theory for the exclusive occurrence of vol- “canoes near the borders of the ocean? Why is it unnecessary to consider the interior of the earth as in a fluid condition like that of the lava ejected from volcanoes ? Name the principal regions ef active volcanoes. What facts have been discovered respecting earthquake shocks? Why should the shocks occur more frequently at night than during the day, or during winter than summer? Into what two classes may unstratified rocks be divided ? Explain the origin of coal. Enumerate some of the changes which are now taking place in the crust of the earth. What are the relative land- and water-areas of the earth? Describe the land hemisphere. The water hemisphere. What do you understand by lines of trend? Which of the continents contains, in proportion to its area, the greatest length of coast line? Which the least? Distinguish between continental and oceanic islands; between coral and volcanic islands. Why does the presence of an atoll in any part of the ocean prove the subsidence of its bed at that point? Ex- plain the nature of the coral formations off the southern coast of Florida. What. do you understand by the forms of relief of the land ? Distinguish between a mountain and a hill. and a plain. What peculiarities are noticeable in the general relief forms of the continents? Which of the continents resemble each other in the gen- eral arrangement of their relief forms? In what respect do they all resemble one another? A plateau The Water. Enumerate the prineipal uses of water in the economy of the earth. What effect has the high specific heat of water on the climate of maritime countries? What is the cause of the heat developed during the con- densation of a mass of vapor? Distinguish between Subterranean and surface drainage. Explain in general the origin of springs. Into what different classes may springs be divided ac- cording to the size of their reservoirs? According to the shape? The location? The shape of the outlet tube ? Define calcareous, silicious, sulphurous, chalybeate, brine, and acidulous springs. Define river-system, basin, water-shed, source, channel, and mouth. Explain the origin of waterfalls. By what are the inundations of rivers caused? What is silt? In what different parts of a river-system may silt be deposited? Define fluvio-marine formations. In what respects do the drainage-systems of North and South America resemble each other?